1. Field of the Invention
The present invention generally relates to platforms for utility trailers and, more particularly, is concerned with a load supporting assembly for a trailer having front and rear pivotal platform sections interconnected by dual actuation linkages and independently pivotable relative to one another and to a middle fixed platform section.
2. Description of the Prior Art
Utility trailers for towing behind vehicles are often used to transport other vehicles, such as tractors, from place to place. A typical utility trailer has an elongated horizontal platform for supporting the vehicle being transported. In the basic utility trailer design, portable ramps are stored and carried on the platform with the vehicle and then temporarily placed at the rear end of the trailer platform for loading and unloading the vehicle onto and from the platform. The problem here is that considerable manual effort is required of the operator to move the portable ramps between their stored and employed positions.
In other trailer designs, the platform itself or at least a pivotal rear ramp portion thereof is movable between inclined and horizontal orientations relative to the ground to avoid the necessity providing and manually moving portable ramps. The platform or ramp portion thereof is placed in the inclined orientation when loading and unloading the vehicle and in the horizontal orientation or in a vertical orientation when transporting the vehicle. A variety of trailers with platforms having pivotal ramps have been proposed over the years for loading, unloading and transporting vehicles on utility trailers. Representative examples of such prior art trailers and the like are disclosed in U.S. Pat. No. 3,690,490 to Hall, U.S. Pat. No. 3,720,335 to Ward, U.S. Pat. No. 3,968,892 to Spors, U.S. Pat. No. 3,972,428 to Love, Jr. et al., U.S. Pat. No. 4,197,048 to Brill, U.S. Pat. No. 4,607,996 to Koch, U.S. Pat. No. 4,813,841 to Eischen, U.S. Pat. No. 4,902,188 to Page, U.S. Pat. No. 5,051,053 to Groeneweg and U.S. Pat. No. 5,328,320 to Farrow et al. However, in the case of most of these designs, considerable manual effort is still required on the part of the operator to move the pivotal ramp portions of these trailer platforms between their employed unloading/loading positions and storage or transport positions.
In still another trailer design as disclosed in U.S. Pat. No. 4,792,274 to Cockram, the utility trailer has a fixed horizontal middle platform and a pivotal front actuating ramp assembly and rear ramp and tailgate assembly pivotally mounted respectively at front and rear edges of the middle platform which are automatically moved between unloading/loading and transport positions with the requirement of manual effort by the operator. The front actuating ramp assembly and rear ramp and tailgate assembly are automatically operated by the action of a mechanical linkage system interconnecting them so as to pivotally move between an inclined orientation relative to the horizontal middle platform for loading and unloading the vehicle and a coplanar horizontal orientation relative to the middle platform for transporting the vehicle.
However, the mechanical linkage system interconnecting the front actuating ramp assembly and rear ramp and tailgate assembly appears to require that they move together and thus that the fixed middle platform of the trailer have a sufficient minimum length to be capable of temporarily receiving and supporting the vehicle solely upon itself as the vehicle is moved between the front actuating ramp assembly and rear ramp and tailgate assembly during loading and unloading. This minimum length requirement of the middle platform of the Cockram trailer for temporarily supporting the vehicle solely thereon results in the provision of a fixed middle platform of substantial length with the front actuating ramp assembly and rear ramp and tailgate assembly, although each shorter in length than the middle platform, adding significantly to the overall trailer length. Further, in Cockram, the middle section is horizontal when the rear ramp section is inclined during loading and unloading in thereby causing a substantial transition between the middle section and the rear section which prevents the loading and unloading of low-clearance vehicles that require a more-or-less continuous ramp.
Thus, the Cockram trailer appears not to provide an optimum solution to the problem of how to load and unload vehicles on and from utility trailers without requiring exertion of considerable manual effort by an operator in that while the Cockram trailer eliminates the above-cited problem but introduces another significant problem in its place by increasing the overall trailer length in addition to not being suited to the loading and unloading of low clearance vehicles.
Consequently, a need remains for an innovation which will provide a more effective solution for loading, unloading and transporting vehicles on utility trailers without introducing any new problems in the process and one which is particularly suited for loading and unloading of low clearance vehicles.